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12-07-0001

PT0225-4

07/04/12

1

Using external 32.768kHz quartz crystal

Real-time clock (RTC) counts seconds, minutes

hours, date of the month, month, day of the week,

and year with leap-year compensation valid up to

2099

31-byte, nonvolatile (NV) RAM for data storage

Time keeping voltage: 1.5V to 5.5V

Uses less than 300nA at 2.0V

Simple 3-wire interface

Serial I/O for minimum pin count

Burst mode for reading/writing successive addresses

in clock/RAM

TTL-compatible (VCC = 5V)

Optional industrial temperature range: -40°C to

+85°C

Battery backup

Trickle charger on chip for rechargeable energy

source backup

The PT7C4302 serial real-time clock is a low-

power clock/calendar with a programmable square-wave

output and 31 bytes of nonvolatile RAM.

Address and data are transferred serially via a 3-

wire bus. The clock/calendar provides seconds, minutes,

hours, day, date, month, and year information. The date

at the end of the month is automatically adjusted for

months with fewer than 31 days, including corrections

for leap year. The clock operates in either the 24-hour or

12-hour format with AM/PM indicator.

Table 1 shows the basic functions of PT7C4302.

More details are shown in section: overview of functions.

X1

X2

GND

VCC1

SCLK

I/O

6

7

8

1

2

3

VCC2

4

5

RST

DIP-8

SOIC-8

1

VCC

2

P

will power the IC.

*1

2

X1

I

Oscillator Circuit Input. Together with X2, 32.768kHz crystal is connected between them.

3

X2

O

Oscillator Circuit Output. Together with X1, 32.768kHz crystal is connected between them.

4

GND

P

5

RST

I

Reset. The reset signal must be asserted high during a read or a write. This pin has a 40k internal pull-

down resistor.

6

I/O

I/

O

Serial Data Input/Output. I/O is the input/output pin for the 3-wire serial interface. The pin has a 40k

internal pull-down resistor.

7

SCL

K

I

Serial Clock Input. SCLK is used to synchronize data movement on the 3-wire serial interface. The pin

has a 40k internal pull-down resistor.

8

VCC

1

P

will power the IC.

*1